How can I limit the visible date range in Merlin Project?
You can limit the visible date range in the Time scale inspector.
Just click a Gantt ruler row to get the Time scale inspector, enter the start and end dates for the visible range.
Per default Merlin Project will hide all tasks planed before and after this period and present a subset of its activities and the respective Gantt. You may however choose to show the other rows while limiting the Gantt.